ComponentsActive / Semiconductor

LCD / OLED Display

Optoelectronic

A display technology that uses liquid crystals (LCD) or organic light-emitting diodes (OLED) to present visual information. Common in smartphones, monitors, and embedded systems.

What it looks like

LCD / OLED Display

A typical optoelectronic — exact shape, colour and markings vary between manufacturers.

Types & variants

Character LCD (16x2, 20x4)Graphic LCD (128x64, 320x240)TFT LCD (color, with backlight)OLED (self-emitting, no backlight needed)Segment LCD (7-segment, custom segments)E-ink (electronic paper, low power)

Key specs

Resolution

pixels (width x height)

Number of pixels on the display (e.g., 128x64, 1920x1080). Higher = more detail.

Interface

Protocol

Communication method: I2C, SPI, parallel, HDMI, MIPI DSI.

Color depth

bits

Number of colors each pixel can display (e.g., 8-bit = 256 colors per channel).

Viewing angle

degrees

Maximum angle where display remains visible (e.g., 178° for IPS panels).

Backlight

cd/m² (nits)

Brightness for LCDs (OLEDs are self-emitting). Higher = better visibility in light.

Markings

Usually has model number printed on the back (e.g., '1602A' for 16x2 LCD). Interface pins labeled on PCB edge.

Standard values

Common resolutions: 128x64, 128x32, 240x240, 320x240. Common sizes: 0.96", 1.3", 1.8", 2.4", 3.5".

How to choose

1) Determine required resolution and size for your application. 2) Check interface compatibility with your microcontroller (I2C vs SPI). 3) Consider color needs (monochrome vs color). 4) Evaluate viewing angle and brightness requirements. 5) Check operating voltage (3.3V vs 5V).

Pinout & package

Typically 8-40 pins. Common pins: VCC, GND, V0 (contrast), RS (register select), RW (read/write), E (enable), D0-D7 (data), A/K (backlight anode/cathode). Packages: module with PCB board, bare glass panel.

Example circuits

  • Arduino with 16x2 LCD via I2C backpack
  • Raspberry Pi touchscreen interface
  • OLED display on ESP32 for IoT status
  • Automotive dashboard cluster display

Common failures

Dead pixels (stuck on/off), backlight failure (no light), damaged connector pins, liquid crystal leakage (dark spots), screen flickering, controller IC failure.

How to test

1) Apply correct voltage and backlight. 2) Send test pattern via microcontroller. 3) Check for uniform backlight and no dead pixels. 4) Verify all segments respond correctly. For OLED, check for color uniformity.

Substitutes

Different size/resolution with same interface. Can use LCD to OLED adapters (with driver changes). Touchscreen versions add touch functionality.

Where to buy

DigiKeyMouserLCSCAdafruitSparkFun